Board Foot Calculator
A board foot is 144 cubic inches of lumber, and this calculator works it the standard way: thickness in inches times width in inches times length in feet times quantity, divided by twelve, so a single 2 x 6 at 8 feet is 8.00 board feet. What it does differently is take a row per board instead of one size at a time, so a whole order totals in one place, and keep the two dimension conventions apart and labelled. The same six 1 x 8 boards at 8 feet bill at 32.00 board feet as nominal sizes and hold 21.75 board feet of wood once surfaced to 3/4 x 7 1/4, and the tool shows you which convention it just used. Thickness takes the rack notation, so 4/4 is 1.00 in, 5/4 is 1.25 in and 8/4 is 2.00 in. Add a price per board foot to cost the pile, then print or copy the cut list.
The total counts the fields above plus every row in the list, so one board never needs adding. Add row (or Enter) moves it to the list and clears the fields for the next size. Thickness takes the rack notation: 4/4 is 1.00 in, 5/4 is 1.25 in and 8/4 is 2.00 in. Every row is rounded to two decimals and the total is the sum of those rows, so the printed lines add up to the printed total.
The cut list
What Print cut list puts on paper, and what Copy puts on the clipboard: a line per size, the convention those sizes were entered in, and the totals.
Board foot cut list Dimensions entered as actual, the sizes a tape measure gives. 1. 1 in x 7 1/4 in x 8 ft, 6 boards: 29.00 bf Total: 29.00 board feet from 6 boards
Nominal sizes and what they measure
The surfaced dry softwood sizes a yard delivers. In Nominal mode the tool bills the size on the ticket and reads this table to tell you what the wood measures; in Actual mode it uses the numbers you typed and leaves the table alone. Hardwood is different again: it is usually sold by quarter thickness, so 4/4 and 8/4 go in the thickness field as 1.00 and 2.00.
| Sold as | Measures | 8 ft board, billed | 8 ft board, measured |
|---|---|---|---|
| 1 × 2 in | 3/4 × 1 1/2 in | 1.33 | 0.75 |
| 1 × 3 in | 3/4 × 2 1/2 in | 2.00 | 1.25 |
| 1 × 4 in | 3/4 × 3 1/2 in | 2.67 | 1.75 |
| 1 × 6 in | 3/4 × 5 1/2 in | 4.00 | 2.75 |
| 1 × 8 in | 3/4 × 7 1/4 in | 5.33 | 3.63 |
| 1 × 10 in | 3/4 × 9 1/4 in | 6.67 | 4.63 |
| 1 × 12 in | 3/4 × 11 1/4 in | 8.00 | 5.63 |
| 5/4 × 4 in | 1 × 3 1/2 in | 3.33 | 2.33 |
| 5/4 × 6 in | 1 × 5 1/2 in | 5.00 | 3.67 |
| 2 × 2 in | 1 1/2 × 1 1/2 in | 2.67 | 1.50 |
| 2 × 3 in | 1 1/2 × 2 1/2 in | 4.00 | 2.50 |
| 2 × 4 in | 1 1/2 × 3 1/2 in | 5.33 | 3.50 |
| 2 × 6 in | 1 1/2 × 5 1/2 in | 8.00 | 5.50 |
| 2 × 8 in | 1 1/2 × 7 1/4 in | 10.67 | 7.25 |
| 2 × 10 in | 1 1/2 × 9 1/4 in | 13.33 | 9.25 |
| 2 × 12 in | 1 1/2 × 11 1/4 in | 16.00 | 11.25 |
| 4 × 4 in | 3 1/2 × 3 1/2 in | 10.67 | 8.17 |
| 4 × 6 in | 3 1/2 × 5 1/2 in | 16.00 | 12.83 |
Common questions
- What is a board foot, and how is it calculated?
- A board foot is 144 cubic inches of lumber: a piece 1 inch thick, 12 inches wide and 1 foot long. Because length is in feet and the other two sides are in inches, the sum is thickness times width times length times quantity, divided by twelve. One 2 x 6 at 8 feet is 2 x 6 x 8 / 12, which is 8.00 board feet, and six boards of 1 in by 7 1/4 in by 8 ft come to 29.00 board feet.
- What is the difference between nominal and actual dimensions?
- Nominal is the size a board is sold and named under; actual is what a tape measure finds after it has been surfaced and dried. A nominal 1 x 8 measures 3/4 x 7 1/4, and a nominal 2 x 4 measures 1 1/2 x 3 1/2. The gap matters: six 1 x 8 boards at 8 feet are 32.00 board feet billed at the nominal size and 21.75 board feet of actual wood. Yards usually bill the nominal size, so this tool bills the numbers you type and, in Nominal mode, prints the surfaced size and the measured board feet beside the total instead of quietly choosing one for you.
- What do 4/4 and 8/4 mean on a hardwood rack?
- They are thicknesses counted in quarter inches, which is how rough hardwood is graded and priced. 4/4 is four quarters, or 1.00 in; 5/4 is 1.25 in; 8/4 is 2.00 in. Type them straight into the thickness field, with the slash, and the calculator reads them as inches. A plain decimal works too, so 1.5 and 6/4 are the same board.
- How do I cost a whole pile of lumber?
- Add a row for each size, using the quantity field for boards that share dimensions, then type your own price per board foot. The cost is your rate times the board feet, worked line by line and added, to the cent, in whatever currency you typed. No price is suggested here: lumber is priced locally, by species and grade, and it moves week to week, so the rate has to be the one your supplier quoted you.
- Is length entered in feet or inches?
- Length is entered in feet, while thickness and width are in inches. That mix is not an oversight, it is the definition: dividing by twelve converts the one foot of length into the twelve inches that make the 144 cubic inches of a board foot. A board 30 inches long is 2.5 feet, so type 2.5.
- Do the printed rows add up to the printed total?
- Yes. Every row is rounded to two decimals, and the total is the sum of those rounded rows rather than a separately rounded figure, so a cut list never argues with itself by a cent. Cost follows the same rule. A row that cannot be read, such as a quantity of half a board or a negative width, is refused with a message naming the row rather than dropped from the total.
Exact arithmetic on the numbers you enter: thickness in inches times width in inches times length in feet times quantity, divided by twelve. What it cannot know is which dimensions your supplier bills on, so nominal and actual are kept separate here and the one in use is shown beside the total.